BILLINGS — Dangerous abandoned uranium mine sites in the Pryor Mountains have been closed following reclamation work aimed at protecting visitors on public lands.
The Bureau of Land Management and the Department of Energy’s Defense-Related Uranium Mine program recently completed work at five historic mine sites in the Pryor Mountains of south-central Montana.
The project, completed in September 2025, addressed 20 mine features, including open mine shafts and other hazards.
Crews backfilled mine openings, installed bat-friendly closure gates, fenced dangerous highwalls, plugged drill holes and removed solid waste.
The BLM says some of the abandoned uranium mines also have elevated levels of metals and radiation in underground workings because of remaining mineralization.
Officials say entering abandoned mines can be dangerous or deadly because the structures can become unstable and collapse over time.
The project began with assessments in 2020 to evaluate physical hazards, radiation levels and chemical contamination at abandoned uranium mine sites.
In 2024, Bat Conservation International conducted additional surveys to identify bat habitat, rare plants and cultural resources that needed to be protected during the closure work.
The BLM issued a decision in August 2025 to move forward with the reclamation work, which was completed the following month.
Officials say the sites will continue to be monitored because erosion, gravity and vandalism can compromise mine closures over time.
The Defense-Related Uranium Mine program is a partnership between the Department of Energy, federal land management agencies and state and tribal abandoned mine lands programs. The program is working to assess and address safety hazards at more than 4,000 abandoned uranium mine sites nationwide.
